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package fr.sii.ogham.sms.builder.cloudhopper;
import java.util.Random;
import fr.sii.ogham.core.builder.Builder;
import fr.sii.ogham.core.builder.context.BuildContext;
import fr.sii.ogham.core.fluent.AbstractParent;
import fr.sii.ogham.sms.splitter.RandomReferenceNumberGenerator;
import fr.sii.ogham.sms.splitter.ReferenceNumberGenerator;
/**
* In the cellular phone industry, mobile phones and their networks sometimes
* support concatenated short message service (or concatenated SMS) to overcome
* the limitation on the number of characters that can be sent in a single SMS
* text message transmission (which is usually 160). Using this method, long
* messages are split into smaller messages by the sending device and recombined
* at the receiving end. Each message is then billed separately. When the
* feature works properly, it is nearly transparent to the user, appearing as a
* single long text message.
*
*
* One way of sending concatenated SMS (CSMS) is to split the message into 153
* 7-bit character parts (134 octets), and sending each part with a User Data
* Header (UDH) tacked onto the beginning. A UDH can be used for various
* purposes and its contents and size varies accordingly, but a UDH for
* concatenating SMSes look like this:
*
*
* - Field 1 (1 octet): Length of User Data Header, in this case 05.
* - Field 2 (1 octet): Information Element Identifier, equal to 00
* (Concatenated short messages, 8-bit reference number)
* - Field 3 (1 octet): Length of the header, excluding the first two fields;
* equal to 03
* - Field 4 (1 octet): 00-FF, CSMS reference number, must be same for all the
* SMS parts in the CSMS
* - Field 5 (1 octet): 00-FF, total number of parts. The value shall remain
* constant for every short message which makes up the concatenated short
* message. If the value is zero then the receiving entity shall ignore the
* whole information element
* - Field 6 (1 octet): 00-FF, this part's number in the sequence. The value
* shall start at 1 and increment for every short message which makes up the
* concatenated short message. If the value is zero or greater than the value in
* Field 5 then the receiving entity shall ignore the whole information element.
* [ETSI Specification: GSM 03.40 Version 5.3.0: July 1996]
*
*
*
* It is possible to use a 16 bit CSMS reference number in order to reduce the
* probability that two different concatenated messages are sent with identical
* reference numbers to a receiver. In this case, the User Data Header shall be:
*
*
* - Field 1 (1 octet): Length of User Data Header (UDL), in this case
* 06.
* - Field 2 (1 octet): Information Element Identifier, equal to 08
* (Concatenated short messages, 16-bit reference number)
* - Field 3 (1 octet): Length of the header, excluding the first two fields;
* equal to 04
* - Field 4 (2 octets): 0000-FFFF, CSMS reference number, must be same for
* all the SMS parts in the CSMS
* - Field 5 (1 octet): 00-FF, total number of parts. The value shall remain
* constant for every short message which makes up the concatenated short
* message. If the value is zero then the receiving entity shall ignore the
* whole information element
* - Field 6 (1 octet): 00-FF, this part's number in the sequence. The value
* shall start at 1 and increment for every short message which makes up the
* concatenated short message. If the value is zero or greater than the value in
* Field 5 then the receiving entity shall ignore the whole information element.
* [ETSI Specification: GSM 03.40 Version 5.3.0: July 1996]
*
*
*
* Configures reference number generation strategy.
*
*
* @author Aurélien Baudet
*
*/
public class ReferenceNumberGeneratorBuilder extends AbstractParent implements Builder {
private final BuildContext buildContext;
private Random random;
private ReferenceNumberGenerator custom;
/**
* Initializes the builder with a parent builder. The parent builder is used
* when calling {@link #and()} method.
*
* @param parent
* the parent builder
* @param buildContext
* for registering instances and property evaluation
*/
public ReferenceNumberGeneratorBuilder(MessageSplitterBuilder parent, BuildContext buildContext) {
super(parent);
this.buildContext = buildContext;
}
/**
* Uses a random number for reference number.
*
* It uses an instance of {@link Random} to generate random numbers.
*
* @return this instance for fluent chaining
*/
@SuppressWarnings("squid:S2245")
public ReferenceNumberGeneratorBuilder random() {
return random(new Random());
}
/**
* Uses a random number for reference number. The provided {@link Random}
* instance is used to generate random numbers.
*
*
* If this method is called several times, only the last {@link Random}
* instance is used.
*
*
* If random parameter is {@code null} then any previously registered
* {@link Random} instance won't be used.
*
* @param random
* the {@link Random} instance used to generate random numbers
* @return this instance for fluent chaining
*/
public ReferenceNumberGeneratorBuilder random(Random random) {
this.random = random;
return this;
}
/**
* Uses a custom reference number generation strategy. This strategy takes
* precedence over any other generation strategy.
*
*
* If this method is called several times, only the last registered
* generator is used.
*
*
* If custom parameter is {@code null}, the custom strategy is disabled.
* Other previously configured strategies (like {@link #random()}) will be
* used instead.
*
* @param custom
* custom reference number generation strategy
* @return this instance for fluent chaining
*/
public ReferenceNumberGeneratorBuilder generator(ReferenceNumberGenerator custom) {
this.custom = custom;
return this;
}
@Override
public ReferenceNumberGenerator build() {
if (custom != null) {
return custom;
}
if (random != null) {
return buildContext.register(new RandomReferenceNumberGenerator(random));
}
return buildContext.register(new RandomReferenceNumberGenerator());
}
}